I just posted the installation instructions in the Technical Resource Library (TRL), in the Sway Bar section, for the '54-'57 & '59-'66 Heavy Duty Anti-Sway Bars being sold by Thunderbirds Southwest. Lance & Pam sent me the 6 page instructions sheets that goes in their kit when you buy one. If you buy either of these bars through them you should get a kit with these instructions in them. If you do NOT get these instructions in the kit, then you have these to fall back on.

These sway bars can be fitted on '54-'57 & '59-'66 Tbirds. Lance said it was not necessary to remove the gas tank for the rear bar install. They do not remove it when they do this install. Notice that '58 Squarebirds are not on the list. Lance said that the OEM coil springs on the '58 prevent this rear bar from being installed. However, if you have done the coil spring replacement with leaf springs, then you should be able to install the rear bar. You will also see that these heavy duty sway bars can be installed on full sized Fords of that era.